1. Field of the Invention
The present invention relates generally to a multi-band antenna, and more particularly to a multi-band antenna suitable for built into an electronic device, such as notebook.
2. Description of the Prior Art
Wireless communication devices, such as cellular phones, notebook computers, electronic appliances, and the like, are normally equipped with an antenna that serves as a medium for transmitting and receiving electromagnetic signals such as data, audio, video or other signals.
In recent years, an inner antenna trends to combine a WLAN (Wireless Local Area Net) antenna and a WWAN (Wireless Wide Area Net) antenna together. WLAN adopts two communications protocols to as Bluetooth and Wi-Fi. Bluetooth works in 2.4 GHz, and Wi-Fi works in 2.4 GHz and 5 GHz. WWAN adopts three communications protocols of GSM (Global System for Mobile Communication), GPS (Global Positioning System) and CDMA (Code Division Multiple Access). Working frequency of the GSM is 900/1800 MHz, and working frequency of the GPS is 1.575 GHz. CDMA includes three kinds of communication protocol to as CDMA2000, WCDMA and TD-SCDMA. Working frequency of the CDMA2000 is 800, 900, 1700, 1800, 1900, and 2100 MHz. Working frequency of the WCDMA is 1800, 1900, and 2100 MHz. And TD-SCDMA is limited in 900, 1800, and 2100 MHz.
Accordingly, it is preferable that an antenna of a notebook could cover above-described working environment, while the portable electronic device is capable of working in WLAN and WWAN. Currently, the portable electronic device is usually built-in with two antennas for respectively working in the WLAN and WWAN. However, portable electronic devices promote to be smaller and thinner so that receiving two antennas therein become more and more difficult and challenging.
U.S. Pat. No. 7,289,071 discloses a multi-band antenna capable of working at WWAN and WLAN environments. The multi-band antenna is capable to work in both WWAN and WLAN at the same time.
However, the such multi-band antenna has comparably limited working frequencies, and is not capable to cover some frequency bands of WWAN. In addition, the design of two antennas sharing the common edge of a grounding element makes the WLAN antenna and the WWAN antenna influence each other to reduce the radiating performance of the antenna.
Hence, in this art, a multi-band antenna to overcome the above-mentioned disadvantages of the prior art will be described in detail in the following embodiment.